How do I apply delta transforms to normal transform?
I ran into the same issue and used Bintang Senja solution. I also used for rotation and scale, maybe the code can help someone else:

import bpy
for obj in bpy.context.selected_objects:
# Store delta location, Eurler rotation and scale of selected objects
obj_deltaL = obj.delta_location
obj_deltaR = obj.delta_rotation_euler
obj_deltaS = obj.delta_scale

# Assign selected objects location, Euler rotation and scale as delta location, Eurler rotation and scale, Reset delta location and Euler rotation to 0 and scale to 1
obj.location = obj_deltaL
obj.delta_location = (0,0,0)
obj.rotation_euler = obj_deltaR
obj.delta_rotation_euler = (0,0,0)
obj.scale = obj_deltaS
obj.delta_scale = (1,1,1)


Please don't juge the code, I know it's crappy. I just wanted a quick and easy solution. It works fine :)